Gasoline fuel compositions



United States Patent() GASOLINE FUEL COMPOSITIONS Theodore R. Lusebrink, Concord, and Stanley L. Cosgrove, Martinez; Califl, assignors to Shell Oil Company, a corporation of Delaware No Drawing. Filed Dec. 1, 1955, Ser. No. 550,491

10 Claims. (Cl. 44--62) This invention relates to improved hydrocarbon compositions boiling substantially within the gasoline boiling range, particularly such compositions designed to be used as fuels in internal combustion engines.

Commercial hydrocarbon compositions boiling in the gasoline boiling range invariably invariably contain small amounts of water, either dissolved or dispersed in the product. This is because it is virtually impossible to prevent contact of the product with water during blending operations, storage, and transportation to'the consumer. Also, even if the greatest precautions to prevent any such contact were taken, water would still be abembed from the atmosphere. The presence of a small amount of water as such is not normally deleterious; however, when the product is cooled, ice particles are often formed.

The formation of ice in such hydrocarbon products is usually at least troublesome and often is extremely dangerous. For example, all gasoline-powered vehicles are normally provided with filters, such as filter screens and micronic filters, in the fuel system, so as'to prevent the passage of solid contaminants, for example, small particles of rust, into the engine. When ice is formed in the gasoline used, it will often plug the filters, thus stopping the fiow of fuel to the engine. In the case of vehicles operating on the ground or water surface, this is at least inconvenient; but in aircraft such stoppage, of course, involves a grave risk tohuman life. Because of this danger, most aircraft are provided with an automatic by-pass around the filters. However, on the opening of the by-pass, the ice is passed through the injector mechanisms and the like, which contain close and critical tolerances. Here, the ice causes still. further difficulties,

including malfunctioning of these mechanisms.

Another fuel system mechanism which is particularly prone to malfunctioning due to plugging with ice is the carburetor. moisture is introduced from the air for combustion. Even though both liquid fuel and air temperatures are above 32 F., the evaporation of the fuel in the carburetor'will often cool the system to 32 F. or-below, especially soon after starting the engine, whereupon ice will form and will frequently cause the engine to stall because of the blocking of fuel and air passages by the ice.

Heretofore, these ditficultie's have sometimes been alleviated by incorporating into the hydrocarbon product certain water-soluble freezing point depressants, such as alcohols, including glycols, or the like. However, this requires relatively large concentrations of the freezing point depressant, for example, from about 0.1% to as high as..2 or 3% by volume. These large concentrations are not only uneconomical but also often adversely aifect the chemical and physical properties of the product. Additionally, the high water solubility of these com- .pounds makes them susceptible to removal from the hydrocarbon product by the leaching action of the free At this pointinthe fuel system, additional water with which the product usually comes in" contact Patented May 2,1961

commercial handling. Although this is by no means del sirable, the alcohols, for example, isopropyl alcohol," still are somewhat effective in decreasing the incidence of stalling of automobiles due to carburetor icing. But in the case of aircraft applications wherein filter clogging is particularly critical, and temperatures are unusually low, the increased concentration of water in the gasoline overbalances the benefit of the freezing point depressant, so the addition of the latter often aggravates rather than alleviates the problem.

It is accordingly a principal object of this invention to provide an improved composition of hydrocarbons boiling within the gasoline boiling range." A" more particular object is to provide such a'composition which has im-' proved characteristics with respect to ice formation there-- in. A further object of the invention is to provide a gasoline fuel composition with improved anti-icing characteristics. Still further an object of the invention is to provide a hydrocarbon composition with improved characteristics with respect to ice formation therein and which requires neither a water soluble anti-icing additive nor a hLgh concentration of an anti-icing additive. Other objects will be apparent from the description of the invention.

' It has now been discovered that these and other objects are attained by the addition, to a hydrocarbon product boiling within the gasoline boiling range, of an extremely small concentration, for example, less than parts per million (wt.), of certain highly-branched oil-soluble organic polymers containing basic nitrogen groups, to be described with particularity hereinafter.

The exact'way that the polymeric additive alleviates icing difficulties is not known. Since the additive is not water soluble, it probably does not act strictly as a freezing point depressant, and so it may'not actually prevent the formation of ice when the hydrocarbon prod:

uct is cooled. However,even if the ice still forms, it is clear that the presence of the additive of the invention prevents, or at least reduces, plugging of screens and interference with the operation of pumps, -injector mecha i nisms, carburetors, and the like.

The hydrocarbon base, material which is the major component of the composition of the invention can be any hydrocarbon or mixture of hydrocarbons boiling substantially within the gasoline boiling range, that is, those with normal boiling points from about 30 F. to about 450 F. The invention is"'particularly directed to mixtures of hydrocarbons within an ASTM boiling range of about 350 F. s v I The polymeric additive of the invention is an oilsoluble polymeric amine having a molecular weightsuch I that its inherent viscosity at 0.1% concentration in ben zene at 25 C .'is at least 0.1 and preferably no greater i than 3.0, containing from about 0.2 to about S%'by" weight of amino nitrogen and having a carbon to amine i nitrogen ratio'of at least 2O to 1'. Polyamines of this, class are well known in the art and have been described V in detail as lubricating -oil and furnace oil .additivesinfl the paper .A New Class of Polymeric Dispersantsgfor Hydrocarbon Systems by Biswell et al.,, presentedat th'e1:

th National Meeting, American Chemical Society Kansas City, Missouri, March 23 ,to April 1,1954. How

by addition copolymerization of two vinylidene monomers, one of which contains no basic nitrogen but contains at least eight carbon atoms and provides an oleophilic structure, and the other of which contains one or more amino nitrogens. These monomers can readily be polymerized in such a ratio of one component to the other that the final copolymer has the desired amino nitrogen content and carbon to amino hydrogen ratio.

As the oleophilic components of these copolymers there I can be employed polymerizable esters, amides, and bydrocarbons characterized by the presence of at least eight carbon atoms, preferably with six or more in a straight hydrocarbon chain, with one terminal carbon to carbon double bond. Examples of such compounds are the saturated and unsaturated long chain esters of unsaturated carboxylic acids, preferably alpha-beta-unsaturated acids, such as decyl acrylate, 3,5,5-trimethylhexyl acrylate, 9- octadecenyl methacrylate; vinyl esters of long chain carboxylic acids, such as vinyl laurate, vinyl stearate; N-long chain hydrocarbon substituted amides of unsaturated acids such as N-octadecyl acrylamide; long chain unsaturated monoolefins such as the alkylstyrenes, e.g., dodecylstyrene; and the like. Especially useful as the oleophilic component is an acrylic acid ester, and in particular, technical lauryl methacrylate.

As the amino nitrogen component there can be employed amino-substituted olefins such as p-(beta-die-thylaminoethyl)styrene; polymerizable amino nitrogen-concontaining heterocycles, e.g., vinylpyridine and the vinyl alkyl pyridines such as 2-vinyl-5-ethylpyridine; vinyl ethers of amino alcohols, such as beta-diethylaminoethyl vinyl ether; amides of unsaturated carboxylic acids having amino substituents on the amido nitrogen, such as N-(beta-dimethylaminoethyl)acrylamide; polymerizable unsaturated amines, such as diallylamine, and as a preferred class, an amino nitrogen-containing ester of an acrylic acid, especially and most usefully acrylic and methacrylic acid esters of N-beta-hydroxyethyl tertiary amines.

As long as the carbon to nitrogen ratio of the polymeric amine is at least 20 to 1 the ratio of the monomers of the copolymer can vary widely. It is preferred, however, that the ratio of the oleophilic monomer to the nitrogen monomer be at least 1:1 and preferably at least 3:2. On the other hand, this ratio should not be greater than about 50:1 and preferably not greater than 25:1. Especially useful copolymers are those wherein this ratio is from about 3:1 to about 20:1. An especially preferred polymeric amine is a copolymer of lauryl methacrylate and betadiethylaminoethylmethacrylate in which these monomers are respectively present in a ratio of from about 80:20 to about 95:5.

It will thus be seen that the polymeric amines have the general formula:

wherein the ratio of x to y is the ratio of the monomers discussed above; wherein R is a hydrogen or a lower ,alkyl group such as methyl or ethyl, wherein O is an oleophilic group preferably saturated such as an alkyl group or alkaryl group, containing a straight chain hydrocarbyl group of at least 6 carbon atoms and preferably 12 to 20 carbon atoms, for example, lauryl, octadecyl, hexadecyl, 2- or 4-octylphenyl or the like; wherein B is a basic nitrogen group, especially an amino-nitrogen group such as a di-lower-alkylaminoalkyl group, or a di-lower-alkylaminoalkaryl group, or a substituted or unsubstituted pyridyl group, for example, beta-diethylaminoethyl, dimethylaminomethyl 4 phenyl, or Z-methyl 4 pyridyl; wherein L and L are linking direct bonds or groups containing no more than 4 atoms at least one of which is oxygen, for example, an oxygen atom, a carbonyloxy group or a carbonylimido group The molecular weights of suitable copolymers generally range from about 50,000 to about 1,000,000, preferably about 100,000 to 500,000. The viscosity of the copolymers will, of course, vary with the molecular weight, generally in the range of from about 5,000 to 50,000 and preferably 8,000 to 30,000 SUS at F.

As before mentioned, the effective concentrations of the copolymers in the hydrocarbon compositions of the invention are extremely small, being generally less than 100 parts per million (wt.). The concentration can be as low as 0.1 part per million in some cases, although it is preferred that at least 1 and especially at least 5 parts per million be used. Also preferred are concentrations no greater than 50 parts per million and usually no greater than 30 parts per million. For best results, especially in aviation gasoline, concentrations no greater than 10 parts per million should be used.

Besides the copolymer, the hydrocarbon compositions of the invention can, and ordinarily will, contain other additives, such as the common commercial additives, for example, anti-detonants such as tetraethyl lead, iron carbonyl, dicyclopeutadienyl iron, xylidene, and N-methyl aniline, lead scavengers such as ethylene dibromide and ethylene dichloride, dyes, spark plug anti-foulants such as tricresyl phosphate, dimethyl xylyl phosphate, and diphenyl cresyl phosphate, combustion modifiers such as alkyl boromic acids and lower alkyl phosphates and phos phites, oxidation inhibitors such as N,N-disecondarybutylphenylenediamine, N-n-butyl-p-aminophenol, and 2, 6-ditertiary-butyl-4-methylphenol, metal deactivators such as N,N'-disalicylal-l,2-propanediamine, and rust inhibitors such as polymerized linoleic acids and N,C-disubstituted imidazolines, and the like.

The invention is illustrated in the following examples which, however, should not be considered limitations thereof.

EXAMPLE I In order to investigate the benefits of various additives in decreasing the tendency of hydrocarbon product filters to plug with ice, a fuel filter icing test was designed as follows: The apparatus consists of a constant flow pump which forces a white oil into a first glass vessel, initially filled with water. The water thus displaced is introduced into a second glass vessel, initially filled with the hydrocarbon product to be tested. The hydrocarbon product thus displaced from the second glass vessel is passed through a heat exchanger, where its temperature is reduced to the desired level, usually between about 0 F. and 20 F., and immediately thereafter through a 10 micron paper filter (Bendix Skinner Division, Bendix Aviation Corporation, Part No. 568,509). In this manner the hydrocarbon product is kept in contact with water, and air is excluded, thus avoiding any change in water concentration in the hydrocarbon product. The flow rate of the hydrocarbon product through the filter was held constant in all tests at 76 cc. per minute. The pressure differential across the filter at any time is therefore a measure of the degree to which the filter is plugged with ice.

' The elapsed time before this differential pressure has reached 16 cm. Hg was selected as a measure of the ability of the hydrocarbon product to avoid plugging of the filter with ice. The higher this figure, of course, the better the hydrocarbon product.

. It has been found that variations in filter temperature between about 0 F. and --20 F. do not have a sub- Table I Concen- Average Time, Additive tration, Tempera- Seconds to p.p.n1. ture at 16 cm.

(wt.) filter, F. Hg 9.

EXAMPLE II Substantially similar beneficial results are obtained with a gasoline containing 10, 30, or 50 parts per million by weight of a 95:5 weight ratio copolymer of decyl acrylate and 4-dimethylaminomethyl styrene.

EXAMPLE III Substantially similar beneficial results are obtained with a 90:10 weight ratio copolymer of lauryl methacryl ate and 4-vinyl pyridine.

EXAMPLE IV Substantially similar beneficial results are obtained with'a 90: 10 weight ratio copolymer of vinyl laurate and vinyl diethylaminoethyl ether.

EXAMPLE V Substantially similar beneficial results are obtained with a 90:10 weight ratio copolymer of lauryl methacrylate and 4-dimethylaminocyclohexyl methacrylamide.

EXAMPLE VI Substantially similar beneficial results are obtained with a 90:10 weight ratio copolymer of dodecylstyrene and diethylaminoethyl methacrylate.

EXAMPLE VII R -'CH2 |JH CH:('lH- I z B V wherein R is selected from the group consisting of hydrogen and lower alkyl radicals, is selected from the group consisting of alkyl and alkaryl radicals containing a straight chain hydrocarbyl group of at least 6 carbon atoms, L and L each contain no more than 4 atoms.

and at least one of which is selected from the group consisting of a direct chemical bond, an oxygen atom, a carbonyloxy group and carbonylimido group, B is an aminonitrogen-containing radical selected from the group consisting of di-lower-alkylaminoalkyl radicals, di-lower-alkylaminoalkaryl radicals and pyridyl radicals, and wherein the ratio of x to y is from about 1:1 to about 50:1

said polymer containing from about 0.2 to about 5% by;

weight of amino nitrogen, having a carbon to amino nitrogen ratio of at least 20:1 and having an inherent vis in benzene at cosity determined at 0.1% concentration 25 C., of 0.1 to 3.0.

2. A gasoline composition in accordance with claim 1, I

wherein L is a carbonyloxy radical and O is an alky radical containing from 12 to 20 carbon atoms. I

3. A gasoline composition in accordance with claim 2, wherein L' is a carbonyloxy radical and B is a di-1ower alkylaminoalkyl radical.

4. A gasoline composition in accordance with claim 3, wherein the concentration of the copolymer is from about 1 to about 50 parts per million by Weight.

5. A gasoline composition in accordance with claim 4, wherein the ratio of x to y is from about 3:1 to about 20:1.

6. A gasoline composition consisting essentially of a major amount of a hydrocarbon material boiling within the gasoline boiling range and from about 1 to about 50 parts per million by weight of an oil-soluble copolymer of lauryl methacrylate and N-beta-diethylaminoethyl methacrylate.

7. An aviation gasoline composition consisting essentially of a major amount of hydrocarbons boiling within the aviation gasoline boiling range and at least about 0.1 and less than about 100 parts per million of a copolymer of lauryl methacrylate and N-beta-dimethylamino ethyl methacrylate containing from about 0.2 to about 5% by weight of amino nitrogen, having a carbon to amino nitrogen ratio of at least 20:1 and having an in! herent viscosity, determined at 0.1% concentration in benzene at 25 C., of 0.1 to 3.0 and wherein the mol ratio of lauryl methacrylate to N-beta-diethylaminoethyl methacrylate in the copolymer is about 9:1.

8. Gasoline containing an antiknock quantity of tetraethyl lead and from about 0.0004 to about 0.01% by weight of a copolymer of lauryl methacrylate and beta-diethylaminoethylmethacrylate having an inherent viscosity of 0.1 to 3.0 as determined at 0.1% weight/volume concentration in benzene at 25 C. and in which the monomers are respectively present in a ratio of from about :20 to about :5.

9. Gasoline containing an antiknock quantity of tetraethyl lead and from about 0.0004 to about 0.01% by Weight of a copolymer of vinyl lauryl ether and vinyl diethylaminoethyl ether having an inherent viscosity 0! 0.1 to 3.0 as determined at 0.1% weight/volume concentration in benzene at 25 C. and in which the monomers are respectively present in a ratio of about 80:20 to about 95:5.

10. An aviation gasoline composition consisting e8- sentially of a major amount of hydrocarbons boiling within the aviation gasoline boiling range and at least about 0.1 not less than about parts per million by weight of a copolymer of lauryl methacrylate and N-- beta-diethylaminoethyl methacrylate in a mol ratio respectively of from about 1:1 to about 50:1 containing from about 0.2 to about 5% by weight of amino nitrogen, having a carbon to amino nitrogen ratio of at least 20 to l and having an inherent viscosity, determined at 0.1% concentration in benzene at 25 C., of 0.1 to 3.0.

References Cited in the file of this patent UNITED STATES PATENTS McNab et al. May 10, 1949 Duncan et al. Apr. 19, 1955 OTHER REFERENCES 

1. A GASOLINE COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF A HYDROCARBON MATERIAL BOILING WITHIN THE GASOLINE BOILING RANGE AND A MINOR AMOUNT, AT LEAST 0.1 AND LESS THAN 100 PARTS PER MILLION BY WEIGHT, OF AN OIL-SOLUBLE COPOLYMER HAVING THE FORMULA: 